Grinding machine

ABSTRACT

A grinding machine having a pair of vertically aligned grinding wheels mounted upon spindles for rotation about parallel axes. Elongated guides extend toward and away from a grinding region disposed between the wheels to guide a plurality of workpieces into engagement with and away from the grinding wheels. The guides provides tunnel-like inlet and outlet guide passages communicating with the grinding region. A large quantity of cooling fluid is supplied to and confined to the grinding region. A loading rail is vertically movable from a loading position wherein a plurality of workpieces can be disposed thereon, to an unloading position wherein the loading rail is aligned with the inlet guide. A reciprocal pushing device is substantially aligned with the loading rail when in its unloading position for causing the workpieces thereon to be pushed through the inlet guide passage and into the grinding region for engagement by the grinding wheels. Suitable retarding and holding structures are associated with the outlet guide for insuring that the workpieces remain closely adjacent one another and for preventing the workpieces from moving backward into the grinding region after retraction of the pushing device.

nited States Patent [1 1 MacKay 1 Oct. 30, 1973 GRINDING MACHINE [57] ABSTRACT [75] Inventor: John A. MacKay, Warren, Mich. A grinding machine having a pair of vertically aligned grinding wheels mounted upon spindles for rotation [73] Asslgnee ggzg figz Madison about parallel axes. Elongated guides extend toward and away from a grinding region disposed between the [22] 7 Filed: Nov. 1, 1 971 wheels to guide a plurality of workpieces into engagement with and away from the grinding wheels. The [211 App]. 1944546 guides provides tunnel-like inlet and outlet guide pas- Related U.S. Application Data sages communicating with the grinding region. A large [63] Continuation-in-part of Ser. No. 1,256, Jan. 7, 19.70, quantity of cooling fluid is pp to and confined to Pat. No. 3,616,579, the grinding region. A loading rail is vertically movable from a loading position wherein a plurality of [52] U.S. Cl. 51/82 R, 51/102 p ces can be disposed thereon, to an unloading [51] Int. Cl B24b 7/12 p i n wherein the l ding rail i lign with the [58] Field of Search 51/82 R, 80 R, 80 A, et guide. A reciprocal pushing device is substan- 51/33 R 84 R 102 tially aligned with the loading rail when in its unloading position for causing the workpieces thereon to be [56] References Cited pushed through the inlet guide passage and into the UNITED STATES PATENTS grinding region for engagement by the grinding wheels. Suitable retarding and holding structures are associated with the outlet guide for insuring that the 2,252,318 8/1941 Somes ct alm SUSO'A I workpieces remain closely adjacent one another and 2 943 03 3 19 0 Eger et I 51/30 A for preventing the workpieces from moving backward 3,350,816 11/1967 Breeding... 51/80 A into the grinding region after retraction of the pushing 3,428,038 2/1969 Hoglund.... 51/80 R X 1 device. 3,616,579 11/1971 MaCKay 51/82 R Primary ExaminerDonald G. Kelly Assistant ExaminerHoward N. Goldberg Attorney-Robert E. Woodhams et al.

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saw mar 14 GRINDING MACHINE CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of my copending US. Pat. application Ser. No. l 256, filed Jan. 7, 1970, and entitled Grinding Machine now US. Pat. No.'3,616,579.

FIELD OF THE INVENTION This invention relates in general to a grinding machine and, more particularly, to a type thereof especially adapted to simultaneously grind two substantially opposed surfaces of a relatively hard workpiece, the grinding operation being performed accurately, automatically and quickly so that the machine can be adapted to high production operations.

BACKGROUND OF THE INVENTION Persons familiar with the use of grinding equipment in performing an operation on relatively hard workpieces have long recognized the difficulties encountered in the grinding of two nonplanar or irregular faces of a hard workpiece, such as one made from Ferrite, while maintaining a specified dimensional relationship between suchfaces. l-ieretofore, it has been customary to grind one face of the workpiece by means of a diamond-surfaced grinding wheel and then grind the second face, often on a second machine. However, especially where the workpiece is small or has an irregular shape, it is extremely difficult to produce uniformly similar pairs of ground faces on the successive parts. Moreover, the existing, two-step process requires at least twice as long for each piece, involves considerable additional handling and usually results in numerous rejects.

For purposes of example, only, specific reference is herein made to a particular workpiece, namely, a fixed field magnet made of Ferrite for a small motor, because this workpiece has given rise to the aforementioned problem of accurately matching the shapes and dimensions of successive pairs of ground surfaces. It is important that the thickness of the field magnet is uniform in order to provide uniformly consistent and effective motorsl In many cases, it is necessary to maintain tolerances of less than five thousandths of an inch and this has not been possible heretofore by means of automatic equipment capable of a large, low-cost output. That is, it has previously been necessary to produce this type of a workpiece either by a high-cost machining operation or by a relatively slow and high-cost, two-step grinding operation, both of which were performed substantially manually.

It is well known that the grinding wheel or grinding wheels must be removed from the spindles of a grinding machine, rather frequently in some instances, to repair them or to replace them with grinding wheels of different contours. Where the workpiece is relatively small, as in the case of a one-piece field magnet for a fractional horsepower motor, such removal has, in the past, been clifiicult. The grinding wheel spindle is usually supported in and extends from both ends of a bearing assembly, and the grinding wheel is sleeved onto one extended end of the spindle. However, parts of the grinding machine, which hold or guide the workpiece, frequently extend across the face of the grinding wheel or wheels, and these parts must be removed before the grinding wheel or wheels can be released from or placed upon the grinding wheel spindles. That is, there is insufficient room for axial movement of the grinding wheel beyond the end of its spindle to permit removal of the grinding wheel. However, in most of these instances there is adequate room for radial movement of the grinding wheel relative to the spindle, in at least one radial direction, if the spindle did not prevent such movement.

Where two radially aligned grinding wheels are used to simultaneously perform a surfacing operation on opposite sides of a workpiece, it is not uncommon to mount the grinding wheels on spindles supported by two separate bearing assemblies which are adjustably mounted upon a supporting column. Where one of the grinding wheels is directly above the other grinding wheel, adjustment of the radial distance between the two grinding wheels is considerably more complicated than where, for example, the two grinding wheels are on the same horizontal level. The weight of the grinding wheel'spindle and bearing assembly can make adjustment difficult and inaccurate. As a result, existing devices for effecting such radial adjustment between a pair of grinding wheels have been complicated and difficult to use, or inaccurate.

Accordingly, a prmary object of this invention is the provision of a grinding machine capable of simultaneously and quickly performing grinding operations on two different surfaces, such as nonplanar or irregular surfaces, of the same workpiece which is fabricated from an extremely hard material, such as Ferrite, while, at the same time, producing a uniformly accurate grinding operation on successive workpieces in a rela tively short period of time.

A further object of this invention is the provision of a grinding machine, as aforesaid, which performs a grinding operation automatically, which is capable of gripping and holding a plurality of workpieces firmly and accurately within a row for permitting said plurality of workpieces to be efficiently and rapidly ground during each cycle of the grinding machine, which is capable of being rapidly cycled to permit the accurate and efficient grinding of large quantities of workpieces within a relatively short time period, and'which can be efficiently operated while requiring only a minimum of operator skill.

Still a further object of this invention is the provision of a grinding machine, as aforesaid, which permits large quantities of cooling fluid, such as water, to be supplied to the grinding region to permit the rapid and efficient grinding of large quantities of workpieces, while at the same time the machine structure and the manner in which it is associated with the workpieces prevents the cooling water from being discharged or thrown externally of the machine.

Another object of the present invention is to provide .a grinding machine, as aforesaid, which includes elongated substantially stationary guide rail structure extending into, through and beyond agrinding region disposed between a pair of grinding wheels for permittting a plurality of workpieces disposed end-to-end within a row to be continuously moved, one 1 after another, through the grinding region, and in which the guide rail structure includes a tunnel-like guide member disposed on the inlet and outlet sides of the grinding region for closely surrounding and confining the incoming and outcoming workpieces to prevent cooling fluid from being discharged therethrough.

Still another object of the present invention is the provision of a grinding machine, as aforesaid, which has loading structure for permitting a plurality of workpieces to be disposed within a row while a further plurality of workpieces is being ground, said firstmentioned plurality of workpieces then being automatically moved into a position in alignment with the inlet guide member after completion of the previous grinding cycle to permit the immediate initiation of a further grinding cycle.

Other objects and purposes of the invention will become apparent to persons familiar with this type of equipment upon reading the following description and examining the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a grinding machine embodying the invention.

FIG. 2 is a side elevational view of the grinding machine, same being illustrated with the protective covers on the housing surrounding the grinding wheels removed and with the loading elevator in its lowered position.

FIG. 3 is a top view of the machine illustrated in FIGS. 1 and 2.

FIG. 4 is an end view of the machine as taken from the right side of FIG. 2.

FIG. 5 is a fragmentary sectional view taken along the line VV in FIG. 6.

FIG. 6 is an enlarged fragmentary side elevational view illustrating therein only the structure directly associated with the grinding region.

FIG. 7 is a top view of the guide rail structure illustrated in FIG. 6.

FIG. 8 is a fragmentary sectional view taken along the line VIII-VIII in FIG. 6.

FIG. 9 is a fragmentary sectional view taken along the line IX--IX in FIG. 6.

FIG. 10 is a sectional view taken along the line X-X in FIG. 6.

FIG. 11 is a top view of the loading and transfer mechanisms.

FIG. 12 is a fragmentary elevational view, partially in cross-section, taken along the line XII-XII in FIG. 11.

FIG. 13 is a fragmentary elevational view taken along the line XIII-XIII of FIG. 11.

FIG. 14 is a fragmentary cross-sectional view taken along the line XIVXIV in FIG. 13.

FIG. 15 is a diagram of the hydraulic circuit of the grinding machine.

FIGS. 16A and 16B are a diagram of the electrical control circuit of the grinding machine.

FIG. 17 is a fragmentary top plan view of an alternate grinding machine embodying the invention.

FIG. 18 is a sectional view taken along the line XVIII- XVIII in FIG. 17.

FIG. 19 is a sectional view taken along the line XIX- -XIX in FIG. 18.

FIG. 20 is a sectional view taken along the line XX-XX in FIG. 18.

Certain terminology will be used in the following description for convenience in reference only, and will not be limiting. For example, the words upper, lower, front and rear will have reference to the machine as appearing in FIGS. 1 and 2 which illustrate the front of the machine. The words inner and outer will refer to directions toward and away from the geometric center of the device and designated parts thereof. Said terminology will include the words above specifically mentioned, derivatives thereof and words of similar import.

SUMMARY OF THE INVENTION The objects and purposes of the invention, including those set forth above, have been met by providing a grinding machine having a base structure adjustably supporting a pair of vertically aligned bearing assemblies, each of which rotatably supports a grinding wheel spindle. The spindles are connected at corresponding ends of each to a pair of separate motors. The other ends of the spindles support a pair of radially aligned grinding wheels. In this particular embodiment, the peripheries of said wheels are respectively concave and convex to define an arcuate grinding region therebetween adapted to receive therein arcuate workpieces. Elongated stationary guide rail structure extends tangentially in opposite directions from the grinding region and includes a passageway corresponding to and only slightly larger than the shape of the workpieces to enable the workpieces to be slidably guided into and away from the grinding region. A reciprocating ram slidably extends into the passageway in the guide rail structure for permitting a plurality of adjacent workpieces to be continuously moved, one after another, into and through the grinding region during a single advancing stroke of the ram.

A movable loading rail, when disposed out of alignment with the guide rail structure, is adapted to have a plurality of workpieces mounted thereon in end-toend relationship within a longitudinally extending row. The loading rail is then movable into alignment with the inlet portion of the guide rail structure after the ram has been fully retracted. The subsequent advancing movement of the ram causes the workpieces to be slidably moved into the passageway of the guide rail structure and through the grinding region, during which movement the loading rail is again moved into a loading position to permit a further plurality of workpieces to be loaded thereon. The guide rail structure, on the opposite sides of the grinding region, is provided with suitable fluid passages for directing cooling fluid directly into the grinding region. A retarder device, which may be either weight or spring actuated, coacts with the row of workpieces discharged from the grinding region for maintaining the workpieces directly adjacent one another.

DETAILED DESCRIPTION FIGS. 1-6 illustrate therein a grinding machine 10 constructed according to the present invention, which machine includes a frame 1 1 having a substantially planar base structure 12. A pair of substantially vertically aligned and vertically spaced grinding wheels 13 and 14 are rotatably supported on the frame and disposed above the base structure 12, whereby the grinding wheels define a small grinding region therebetween adapted to receive workpieces. A loading mechanism 16 (FIGS. 1 and 3) projects forwardly of the machine for permitting a plurality of workpieces W to be positioned thereon substantially within a longitudinally extending row, whereupon the row of workpieces is then slidably moved onto a transfer mechanism 17 (FIG. 2). The transfer mechanism 17 is, in the illustrated embodiment, constructed as an elevator mechanism whereby the workpieces are then moved vertically upwardly into alignment with an inlet guide rail structure 18. A pusher mechanism 19 is disposed for engaging the row of workpieces on the transfer mechanism 17 and pushing same into and through the inlet guide rail structure 18 and into the grinding region defined between the wheels 13 and 14. The pushing mechanism then causes the workpieces to be pushed into an outlet guide rail structure 21, and further through a retarder device 22, whereupon the finished workpieces are discharged from the machine, such as onto a conventional discharge conveyor 23. i

The grinding wheel 13, as illustrated in FIGS. 4 and 5, is secured to the outer end of a spindle assembly 26 rotatably supported on a bearing assembly 27, the latter being mounted on an upwardly extending pedestal 28 which comprises a portion of theframe 11. The grinding wheel 14 is similarly mounted on the outer end of a spindle assembly 29 rotatably supported by a further bearing assembly 31 which is also mounted on the pedestal 28. The rearward end of spindle assembly 26 is interconnected to a drive motor 32 by an intermediate belt drive 33, and the other spindle assembly 29 is similarly connected to a further drive motor 34 by a further intermediate belt drive 36. The motors 32 and 34 are each mounted on an upwardly extending column- 37 which also comprises a portion of the frame 11. The bearing ssemblies27 and 31 are each preferably individually adjustable within a plane containing therein the axes of the spindle assemblies 26 and 29 for permitting the grinding wheels 13 and 14 to be vertically moved toward or away from each other to thus accommodate the desired workpiece thickness. The structure for permitting the vertical adjustment of the individual bearing and spindle assemblies, and the specific structure of the bearing and spindle assemblies, is disclosed in greater detail in my above-mentioned copending US. Pat. application Ser. No. 1' 256, now US. Pat. No. 3,616,579, particularly in FIGS. 3 and 9 thereof.

In the illustrated embodiment, the grinding wheels 13 and 14 have coacting concave and convex peripheral grinding surfaces (see FIG. 5) which are slightly radially spaced to define an arcuate grinding region there between, which region is designed to permit workpieces having an arcuate or U-shaped configuration to pass therebetween. However, the grinding surfaces as formed on the wheels 13 and 14 could have any desired configuration to permit simultaneous grinding of opposite workpiece surfaces, such as arcuate or irregular surfaces. The grinding wheels 13 and 14 are disposed within and substantially totally enclosed by a boxlike shroud 38 (FIG. 2) for confining the cooling fluid utilized during the grinding operation.

The workpieces are slidably guided into the grinding region defined between the wheels 13 and 14 by means of the tunnel-like inlet guide rail structure 18 which, as illustrated in FIGS. 6-8, includes an elongated center rail 39 fixedly secured to a base pedestal 12A,'as by screws 41, and having an upper convex guide surface 42 thereon. The end surface of the center guide rail 39 terminates directly adjacent the periphery of the grinding wheel 14 and has a profile corresponding to the circular and axial profile of the wheel so that the rail is thus closely adjacent to and substantially uniformly spaced from the wheel across the complete width thereof.

A pair of parallel side rails 43 and 44 are disposed on opposite sides of the center rail 39. The side rails extend upwardly above the opposite sides of the convex guide surface 42 and have oppositely inclined guide surfaces 46 and 47 formed thereon for engagement with the opposite edges of a workpiece. The center rail 39 and side rails 43 and 44 are substantially surrounded by a downwardly opening channel-shaped cover 48 which is fixedly secured to the base pedestal 12A by any conventional means, such as screws 49. The cover 48 includes opposite leg portions 51 and 52 which bear on the base pedestal 12A and are disposed directly adjacent the external sides of the side rails 43 and 44. The upper ends of the legs 51 and 52 are interconnected by a top wall 53 which has an internal concave guide surface 54 disposed upwardly from and directly opposite the convex guide surface 42. The opposed guide surfaces 42 and 54, and the opposed guide surfaces 46 and 47, thus define an inlet passageway 56 having an arcuate cross-section and extending longitudinally throughout the complete length of the inlet guide rail structure 18. The passageway 56 has a configuration which is substantially the same as, but slightly larger than, the workpieces W to provide a close confining structure for accurately guiding the workpieces into the grinding region.

The end of the top wall 53 directly adjacent the grinding wheel 13 is also provided with a profile thereon which corresponds to both the circular and axial profile formed on the periphery of the grinding wheel 13. For-this purpose, the upper end wall of the guide rail structure 18 is formed with an arcuate configuration S7 generated substantially about the rotational axis of the wheel 13, with the center portion 58 of the end wall projecting outwardly to extend into the recess defined by the concave periphery of the wheel 13.

The top wall 53 also has a flow passage 59 extending therethrough and terminating in a discharge opening 61 disposed directly adjacent the periphery of the wheel 13. The other end of passage 59 terminates in an inlet opening 62 which is connected a suitable conduit (not shown) for permitting cooling fluid, such as water, to be supplied to the grinding region. A further flow passage 63, defined by an undercut recess formed in the end of center rail 39, communicates with a further conduit 64 for permitting 'a further stream of cooling fluid to be discharged into the grinding region directly adjacent the periphery of the lower wheel 14.

The side rails 43 and 44 extend longitudinally of the grinding machine in a direction substantially perpendicular to the plane defined by the rotational axes of the grinding wheels 13 and 14. The rails 43 and 44 are laterally spaced apart by a sufficient distance to enable same to pass on opposite axial sides of the grinding wheel 14, whereby the rails 43 and 44 thus not only comprise a portion of the inlet guide rail structure 18, but also extend through the grinding region and comprise a portion of the outlet guide rail structure 21. The guide rails 43 and 44 also extend through the retarder device 22, with the rightward ends of the rails terminating adjacent the edge of the frame pedestal 128 (FIG. 6). The side rails 43 and 44 thus support and guide the workpieces as they move through the grinding region between the wheels 13 and 14.

, Considering now the tunnel-like outlet guide rail structure 21, same is substantially identical to the inlet guide rail structure 18 and includes a center guide rail 66 (FIG. 9) fixedly secured to the frame pedestal 12B and having an upper convex guide surface 67. The center rail 66 has the side rails 43 and 44 disposed on opposite sides thereof, with same in turn being substantially surrounded by a downwardly opening channelshaped cover 68 which is substantially identical to the previously described cover 48. The cover 68 also has an internal concave guide surface spaced opposite the guide surface 67 to define therebetween an outlet passageway 71 aligned with the inlet passageway 56. Passageway 71 also has a configuration substantially the same as but slightly larger than the cross section of the workpieces.

The forward ends of the center rail 66 and cover 68 terminate directly adjacent the periphery of the wheels 14 and 13, respectively, and have a configuration corresponding to the circular and axial profiles formed on the peripheries of the wheels. The top wall of the cover 68 also has a fluid passage 72 therethrough adapted to be connected to a conduit 73 (FIG. 1) for discharging cooling fluid directly into' the grinding region adjacent the periphery of the upper wheel 13. The center rail 66 also has a fluid passage 74 (FIG. 6) connected to a conduit 76 for permitting the discharge of liquid coolant directly into the grinding region adjacent the periphery of the lower wheel 14. I

The outlet guide rail structure 21 also has a holding device associated therewith for preventing the workpieces, after they have passed through the grinding region, from being moved back into the grinding region by the pressure or suction created by the streams of cooling fluid. For this purpose, the outlet rail structure 21 has a holding lever 77 disposed within the forward end of the fluid passage 72 and pivotally mounted on the cover 68 by means of a transversely extending pivot pin 78. The free end of the lever 77 has a downwardly projecting tooth 79 positioned adjacent the periphery of the wheel 13. The tooth 79 extends through a small elongated slot 81 (FIG. 7) formed in the wall 82 which separates the fluid passage 72 from the guide opening 71. The tooth 79 extends downwardly into the guide opening 71, but has a cam surface 83 formed on the lower side thereof to permit it to be cammed upwardly when workpieces pass through the guide opening 71. The purpose of the holding lever 77, and the manner in which it coacts with the workpieces, will be explained in greater detail hereinafter.

The side rails 43-44 and center rail 66 also extend rearwardly beyond the cover 68 so as to be partially surrounded by the retarder device 22. The retarder device 22, as illustrated in FIGS. 6 and 9, comprises a downwardly opening channel-shaped member 84 which is hingedly supported on a pair of opposed brackets 86 by means of hinge bolts 87. The brackets 86 are fixedly secured to the frame pedestal 128. The channel member 84 is hingedly supported adjacent its leftward end, so that the weight of the channel member 84 causes the rightward-end thereof to pivot downwardly (clockwise in FIG. 6 whereby the internal concave surface 88 formed thereon bears against the upper surfaces of the workpieces W as they are slidably moved longitudinally (rightwardly in FIG. 6) of the rails. The channel member 84 thus exerts a frictional drag on the workpieces which tends to impede their rearward (rightward) movement so that the workpieces disposed forwardly of the device 22 remain in end-toend contact with one another.

While retarder device 22 may operate solely due to its own weight, same may be entirely replaced or supplemented by a spring-urged retarder having springs 89 for urging channel member 84 into frictional engagement with the workpieces.

Alternately, the retarder device 22 may be replaced by a fluid pressure cylinder substantially aligned with the workpieces for applying a retarding force thereto, as disclosed in my above-mentioned copending application.

The rearward ends of the side rails 43 and 44 and the center rail 66 are fixedly interconnected by means of a bolt 91 (FIGS. 6 and 7) extending transversely therebetween. The bolt 91 extends through enlarged openings 92 formed in the side rails for permitting the side rails to be vertically adjusted relative to the center rail 66. For this purpose, there is additionally provided a pair of eccentric adjusting devices 93 and 94 associated with the inlet and outlet guide rail structures 18 and 21, respectively. The eccentric adjusting devices 93 and 94 are identical and thus only the device 93 will be described in detail.

The eccentric adjusting devices 93 (FIG. 8) includes an eccentric sleeve having three cylindrical portions 96, 97 and 98. The cylindrical portions 96 and 98 are coaxially aligned but are eccentric relative to the intermediate cylindrical portion 97, which portion 97 is rotatably supported in the center rail. The eccentric sleeve also has an opening 99 extending longitudinally thereof, which opening is concentric with the intermediate cylindrical portion 97. An elongated screw 101 extends through the opening 99 and has the end thereof threadably engaged within a threaded opening 102 formed in the leg 52 of the cover 48. The other end of the screw 101 has a head 103 disposed in abutting engagement with a hexagonal portion 104 which is fixedly, here integrally, connected to the exposed end of the portion 96. The screw 101, when tightened, prevents rotation of the eccentric sleeve.

To permit the rails 43 and 44 to be vertically displaced relative to the center rail 39, the eccentric cylindrical portion 96 is snugly but rotatably received in an opening 106 formed in the side rail 43, while the eccentric cylindrical portion 98 is snugly but rotatably received within a coaxially aligned opening 107 formed in the side rail 44. A further opening 108, formed in the cover leg 51, is substantially larger than the cylindrical portion 96 to permit it to freely and eccentrically rotate within the opening 108. Thus, by attaching a suitable tool, such as a wrench, to the hexagonal portion 104, the eccentric sleeve can be rotated whereby the eccentric sleeve portions 96 and 98 coact with the rails 43 and 44 to thus cause them to be vertically displaced relative to the center rail 39. Accordingly, by suitable rotation of both eccentric devices 93 and 94, the rails 43 and 44 can be moved vertically relative to the center rails 39 and 66 to permit the grinding machine to accommodate workpieces having slightly different shapes or sizes.

The workpieces W are slidably advanced along the side rails 43 and 44 by means of the pusher mechanism 19 which, as illustrated in FIGS. 2, 3, 6 and 10, includes a fluid pressure cylinder 109 having a reciprocal piston rod 111 extending therefrom,. The end of the piston rod 111 is secured to a ram having a slide block 112 which is slidably supported on a pair of parallel guide rods 113 and 114 disposed on opposite sides of 9 the piston rod 111. The guide rods 113 and 114 extend between and are stationarily mounted on a pair of fixed frame plates 116 and 117 (FIG. 2). The slide block 112 has a recess 118 (FlG. formed in the rearward side thereof, and a mounting block 119 is disposed within the recess 118 and fixedly connected to the slide block 112 by screws 121. The mounting block 119 has an elongated pushing member 122 fixedly secured thereto 7 and extending outwardly therefrom, which pushing member 122 is adapted to slidably extend into the passageways 56 and 71. The pushing member 122 has an arcuate cross-section substantially the same as but slightly smaller than the arcuate cross-section of the passageways, whereby the free end of the pushing member 122 can thus engage a workpiece W to slidably move a row of said workpieces through the passageway 56, through the grinding region between the wheels 13 and 14, and into the passageway 71. The pushing member is thus of substantial length so that the free end of the pushing member 122 extends at least part way into the passageway 71, as illustrated by dotted lines in FIG. 6, when the ram 1 10 is in its forward position. This thus causes the endmost workpiece to be disposed beyond the tooth 79 formed on the holding lever 77. When in this extended position, the slide block 112 is positioned directly adjacent, the leftward ends of the side rails 43 and 44, substantially as illustrated in FIG. 6. On the other hand, when the ram 110 is in its fully retracted position, then the free end of pushing member 122 is spaced leftwardly a substantial distance from the ends of the side rails 43 and 44, as illustrated by the dotted line position 122A in FIG. 6, to thus permit a new row of workpieces to be moved upwardly by the transfer mechanism 17 into the space between the pushing member 122A and the inlet guide rail structure 18. This latter-mentioned positional relationship of the transfer mechanism 17 is illustrated by dotted lines in FIG. 6.

The transfer mechanism 17, as illustrated in FIGS. 1 1 and 12, includes a turntable 123 secured to the upper end of a support post 124. Thesupport post is rotatably and slidably supported within an annular bearing plate 126 held in position by a sleeve 127 fixedly connected between the bearing plate 126 and a stationary mounting plate 128. The mounting plate 128 is secured to the upper end of a fluid pressure cylinder 129 which, at its lower end, is stationarily mounted on a frame plate 131. The cylinder 129 has a reciprocal piston rod 132 extending from the upper end thereof, which piston rod is axially connected to the lower end of support post 124 by a swivel member 133 for permitting support post 124 to freely rotate relative to the piston rod 132.

The base structure 12 has a plate 134 rigidly secured relative thereto, which plate mounts thereon a radially projecting roller 136. Roller 136 extends into a curved cam groove 137 formed in a cam member 138 fixedly secured to the inner surface of an annular sleeve 139 attached to and extending downwardly from the lower surface of the turntable 123. The annular sleeve 139 extends into a stationary annular shroud 141. The cam groove 137 is curved to extend both circumferentially and axially so that vertical movement of the turntable 123 between its lowermost and uppermost positions also causes a predetermined angular displacement thereof.

The vertical travel of the transfer mechanism 17 is controlled by a pair of limit switches LS-4 and LS-S disposed below the fluid pressure cylinder 129. The piston rod 132 extends from the lower end of the cylinder and has a pair of switch cams 146 and 147 threadedly mounted thereon, which cams are disposed for contact with the limit switches LS-4 and LS-S, respectively, when the turntable is in its respective upper and lower positions.

The turntable l23'is provided with a transfer rail 148 secured to the upper surface thereof and extending substantially radially thereof. The transfer rail 148 includes a center rail portion 149 having an upper convex surface and a pair of side rail portions 152 and 153 having oppositely tapered guide surfaces formed on the upper ends thereof. The transfer rail 148 thus has a cross-sectional configuration substantially the same as the center rail and side rails of the inlet guide rail structure 18. Thus, a plurality of workpieces W can be disposed in a row in end-to-end relationship on the transfer rail when same is in the lowered loading position illustrated by solid lines in FIGS. 11 and 12, with the row of workpieces then being slidably moved by the pushing member 122 from the transfer rail 148 into the inlet guide rail structure 18 when the transfer mechanism has been moved into the raised unloading position illustrated by dotted lines in FIGS. 11 and 12.

When the turntable 123 of the transfer mechanism 17 is in its lowered position, as illustrated by solid lines in FIGS. 11 and 12, the rail 148 is directly adjacent and substantially aligned with the loading mechanism 16 so that a row of workpieces on the loading mechanism 16 can be slidably moved onto the rail 148, whereby energization of the transfer mechanism causes the row of workpieces to be moved angularly and upwardly to a position in alignment with the passageway 56 formed by the inlet guide rail structure 18. In order to permit this loading operation to be performed, the loading mechanism 16 146 (see FIGS. 1144) includes an elongated loading rail 157 which is substantially identical in cross-section to the transfer rail 148. The loading rail 157 is fixedly mounted on a horizontal frame element 156 and projects outwardly from the front side of the machine to thus be readily accessible to an operator standing infront of the machine. This thus permits the operator to position a plurality of small arcuate workpieces W on the loading rail 157, with the workpieces being positioned substantially adjacent one, another to thus form a longitudinally extending row of workpieces.

The loading mechanism 16 also includes a pair of substantially parallel guide rods 158 disposed on opposite sides of the loading rail 157 and supported at their opposite ends by stationary brackets 159. A U-shaped slide block 161 is slidably supported on the guide rods 158and is fixedly secured to one end of an elongated transfer slide 162, which slide has the forward end thereof spaced above and movable along the loading rail 157. The transfer slide 162, as illustrated in FIG. 14, has an'arcuate cross-section similar to the crosssection of the workpieces W. The transfer slide 162 also has a handle 163 to permit the transfer slide to be manually or power actuated for movement between a retracted position as illustrated by solid lines in FIG. 13 and an advanced position as illustrated by dotted lines in FIG. 13.

CONTROL SYSTEMS The hydraulic and electrical control systems for the 

1. A machine for successively grinding a plurality of workpieces, comprising: base means; a pair of bearing assemblies supported upon said base means, at least one of said assemblies being adjustable toward and away from the other; a pair of parallel spindles, one thereof being rotatably supported in, and extending from, each of said bearing assemblies; driving means supported by said base means and connected to said spindles for rotating same; a pair of radially aligned grinding wheels mounted upon the extended ends of said spindles, said grinding wheels having their peripheries near to but spaced from one another to define a grinding region therebetween; elongated, substantially horizontal guide structure associated with said grinding region for guiding a group of workpieces toward, through, and away from said grinding region, said guide structure extending substantially tangentially between said wheels; said guide structure including tunnel-like inlet and outlet guide means extending away from said region, the adjacent ends of said inlet and outlet guide means being positioned closely adjacent the peripheries of said grinding wheels, said inlet and outlet guide means having passageways extending therethrough and communicating directly with said grinding region, said passageways having cross-sections substantially the same as, but slightly larger than, the cross-section of the workpieces; and drive means, including a reciprocating pushing member, for engaging a row of workpieces for slidably moving the workpieces through the passageway of the inlet guide means, through the grinding region and into the passageway of the outlet guide means.
 2. A grinding machine according to claim 1, wherein each of said inlet and outlet guide means includes a fluid passage therethrough and terminating directly adjacent said grinding region for permitting streams of cooling fluid to be discharged directly into said grinding region from opposite sides thereof.
 3. A grinding machine according to claim 1 for simultaneously grinding opposite concaVe and convex surfaces of a workpiece, wherein one of said grinding wheels has a convex periphery and the other grinding wheel has a concave periphery, whereby said peripheries define a grinding region therebetween substantially corresponding to the cross-section of said workpieces; said elongated guide structure including a pair of elongated parallel and spaced guide rails extending horizontally along the opposite axial sides of said other grinding wheel, said pair of guide rails comprising a portion of said inlet and outlet guide means and also extending through said grinding region for slidably supporting the workpieces as they move therethrough; and said inlet and outlet guide means each including a center rail disposed between said side guide rails and terminating directly adjacent said grinding region, each center rail having an upper surface adapted to slidably support one of the external surfaces of said workpiece.
 4. A grinding machine according to claim 3, wherein the upper surface of each center rail has a convex configuration, and each of said inlet and outlet guide means also having a top wall having a lower concave surface spaced above the upper convex surface of its respective center rail for defining said passageway therebetween.
 5. a grinding machine according to claim 4, wherein the top wall of each guide means has a fluid passage extending therethrough and communicating with said grinding region directly adjacent the periphery of the uppermost grinding wheel for permitting streams of cooling fluid to be directed into said grinding region from opposite sides of a plane defined by the axes of said spindles, and each of said center rails also having a fluid passage therein communicating with said grinding region directly adjacent the periphery of the lowermost grinding wheel for also directing a pair of streams of cooling fluid into said grinding region from the opposite sides of said plane, and said workpieces when disposed within said guide passageways substantially totally closing same for preventing the cooling fluid from being discharged through the passageways formed in said inlet and outlet guide means.
 6. A grinding machine according to claim 3, further including a retarder device disposed adjacent the other end of said outlet guide means for engaging said workpieces and imposing a retarding force thereon in opposition to the pushing force imposed on said workpieces by said pushing member.
 7. A grinding machine according to claim 3, further including loading means for permitting one group of workpieces to be disposed in an end-to-end relationship within a longitudinally extending row while said pushing member is simultaneously pushing another group of workpieces through the grinding region; and transfer means coacting with said loading means for permitting said one group of workpieces to be moved into a position substantially in alignment with the passageway of said inlet guide means after completion of a previous grinding cycle and retraction of the pushing member.
 8. A grinding machine according to claim 7, wherein said loading means includes an elongated substantially horizontally extending rail structure adapted to have said one group of workpieces positioned thereon, and means mounting said rail structure for substantially horizontal swinging movement between a first position wherein the rail is inclined at an angle relative to the longitudinal direction of the passageway of said inlet guide means and a second position wherein said rail is substantially aligned with said passageway.
 9. A grinding machine according to claim 7, wherein said loading means includes an elongated rail structure-adapted to have said one group of workpieces loaded thereon, and means mounting said rail structure for movement between a loading position wherein said rail structure is substantially vertically spaced from the passageway of said inlet guide means and a unloading position wherein said rail structure is substantially aligned with tHe passageway of said inlet guide means.
 10. A grinding machine according to claim 7, wherein said loading means includes elongated stationary loading rail means, and means mounting same in a stationary position, said loading rail means having a configuration permitting said one group of workpieces to be loaded thereon; said loading rail means being angularly inclined relative to the longitudinal direction of said guide structure and being disposed at an elevation substantially below said guide structure; said transfer means including elevator means mounted for movement between a lowered loading position and a raised unloading position, said elevator means having elongated transfer rail means mounted thereon adapted to slidably receive thereon said one group of workpieces, and means for causing horizontal angular movement of said transfer rail means between first and second rotational positions, said transfer rail means being disposed directly adjacent and in alignment with said loading rail means when said elevator is in said lowered loading position and said transfer rail means is in said first rotational position, said transfer rail means being in alignment with and substantially adjacent said inlet guide means when said elevator means is in said raised unloading position and said transfer rail means is in said second rotational position; and said loading means including reciprocal slide means for engaging said one group of workpieces mounted on said loading rail means for slidably moving same onto said transfer rail means when said transfer rail means is in said first rotational position and said elevator means is in said lowered loading position.
 11. A grinding machine according to claim 10, wherein said pushing member, when in its fully retracted position, is spaced from said one end of said inlet guide means by a distance sufficient to permit said transfer rail means to be disposed therebetween when said elevator is in said raised unloading position, whereby extension of said pushing member causes same to engage said one group of workpieces on said transfer rail means and slidably push same into the passageway of said inlet guide means.
 12. A machine for successively grinding a plurality of workpieces, comprising: base means; a pair of bearing assemblies supported upon said base means; a pair of spindle assemblies, one thereof being rotatably supported in, and extending from, each of said bearing assemblies; first drive means supported by said base means and connected to said spindles for rotating same; a pair of radially aligned grinding wheels mounted upon said spindles, said grinding wheels having their peripheries near to but spaced from one another to define a grinding region therebetween; elongated guide structure associated with said grinding region for guiding a group of workpieces towards, through and away from said grinding region, said guide structure including tunnel-like inlet and outlet guide means extending toward and away from said grinding region, respectively, the adjacent ends of said inlet and outlet guide means being positioned closely adjacent the periphery of said grinding wheels, said inlet and outlet guide means having passageways extending therethrough and communicating directly with said grinding region, said passageways having configurations for accommodating but closely confining the workpieces as they are slidably moved therethrough; and second drive means for engaging the workpieces for slidably moving the workpieces through the passageway of the inlet guide means, through the grinding region and into the passageway of the outlet guide means.
 13. A grinding machine according to claim 1, further including a retarder device disposed adjacent the other end of said outlet guide means for engaging said workpieces and imposing a retarding force thereon in opposition to the pushing force imposed on said workpieces by said pushing member.
 14. A grinding machine according to claim 1, further including loading means for permitting one group of workpieces to be disposed in an end-to-end relationship within a longitudinally extending row while said pushing member is simultaneously pushing another group of workpieces through the grinding region; and transfer means coacting with said loading means for permitting said one group of workpieces to be moved into a position substantially in alignment with the passageway of said inlet guide means after completion of a previous grinding cycle and retraction of the pushing member.
 15. A grinding machine according to claim 14, wherein said loading means includes an elongated substantially horizontally extending rail structure adapted to have said one group of workpieces positioned thereon, and means mounting said rail structure for substantially horizontal swinging movement between a first position wherein the rail is inclined at an angle relative to the longitudinal direction of the passageway of said inlet guide means and a second position wherein said rail is substantially aligned with said passageway.
 16. A grinding machine according to claim 14, wherein said loading means includes an elongated rail structure adapted to have said one group of workpieces loaded thereon, and means mounting said rail structure for movement between a loading position wherein said rail structure is substantially vertically spaced from the passageway of said inlet guide means and a unloading position wherein said rail structure is substantially aligned with the passageway of said inlet guide means. 